Semiconductor photodetector, device for multispectrum detection of electromagnetic radiation using such a photodetector and method for using such a device

Abstract

This semiconductor photodetector consists of a diode with at least two heterojunctions comprising two external layers, a first layer with a given kind or type of doping and a second layer with a kind or type of doping opposite to that of the first layer, the bandgap width of these two layers being determined as a function of the energy and hence the wavelength or wavelength band that they are each intended to detect, these two layers being separated from each other by an intermediate layer having the same kind or type of doping as one of said first and second layers, said diode being subjected to a bias voltage of adjustable value between the two external layers. The bandgap width of the intermediate layer is greater than that of the layer that has the same type of doping as layer.

1. A semiconductor photodetector consisting of a diode with at least two heterojunctions comprising two external layers, a first layer with a given kind or type of doping and a second layer with a kind or type of doping opposite to that of the first layer respectively, the bandgap width of these two layers being determined as a function of the energy and hence the wavelength or wavelength band that they are each intended to detect, these two layers being separated from each other by an intermediate layer having the same kind or type of doping as one of said first and second layers, said diode being subjected to a bias voltage of adjustable value between the two external layers wherein the bandgap width of the intermediate layer is greater than that of the layer which has the same type of doping as the intermediate layer. 
   
   
     2. A semiconductor photodetector as claimed in  claim 1 , wherein the concentration of the doping of the intermediate layer is less than that of the external layer which has the opposite type of doping. 
   
   
     3. A semiconductor photodetector as claimed in  claim 1 , wherein the thickness of the intermediate layer is less than that of the two external layers. 
   
   
     4. A semiconductor photodetector as claimed in  claim 1 , wherein the intermediate layer is itself subdivided into several sub-layers having the same type of doping but different doping concentrations and different bandgap widths. 
   
   
     5. A semiconductor photodetector as claimed in  claim 4 , wherein the highest doping concentration of said sub-layers is located in a first sub-layer that is in contact with an external layer having a kind or type of doping that is different or opposite to that of said first sub-layer. 
   
   
     6. A semiconductor photodetector for obtaining multispectrum detection of electromagnetic radiation, comprising a series-connected arrangement of two multiheterojunction diodes as claimed in  claim 1 , and three layers to collect photons that constitute the incident radiation, the two outermost layers having the same kind or type of doping that is opposite to the type of doping of a middle layer, switching between the two operating modes of each of said heterojunction diodes and respectively being made possible by inserting an intermediate layer and respectively between the two layers that constitute said diodes. 
   
   
     7. A semiconductor photodetector for obtaining multispectrum detection of electromagnetic radiation, comprising a series-connected arrangement of two multiheterojunction diodes as claimed in  claim 1 , and four layers to collect photons that constitute the incident radiation, the two outermost layers having the same kind or type of doping that is opposite to the type of doping of the middle layers, switching between the two operating modes of each of said heterojunction diodes and respectively being made possible by inserting an intermediate layer respectively between the two layers that constitute the diodes, middle collector layers being also separated by a barrier layer having the same type of doping as said layers in order to isolate the collection of photo carriers in the two areas that it separates. 
   
   
     8. A multispectrum electromagnetic radiation detection device, comprising an array of pixels each consisting of a photodetector as claimed in  claim 1 . 
   
   
     9. A multispectrum electromagnetic radiation detection device as claimed in  claim 8 , wherein said pixels are connected to a read-out circuit by means of hybridisation using indium beads. 
   
   
     10. A method for using a multispectrum detection device that contains photodetectors as claimed in  claim 1 , comprising:
 applying a first voltage to said device in order to detect the photo carriers created in the external layer that is differently or oppositely doped to the intermediate layer; 
 then applying a second voltage having a value higher than that of said first voltage in order to detect the photo carriers created in the two external layers; and 
 then subtracting the two quantities thus obtained in order to determine the number of photo carriers created by the second external layer.